Recent STAR Jet Results of the High-Energy Spin Physics Program at RHIC

TL;DR

This paper reports recent results from STAR on jet and dijet double spin asymmetries in polarized proton collisions, providing insights into the polarized gluon distribution in the proton across different energy scales.

Contribution

It presents new measurements of jet and dijet asymmetries at 510 GeV, extending the kinematic range and improving constraints on the polarized gluon distribution.

Findings

Results are consistent across different energies in overlapping x regions.

New data at 510 GeV have higher statistical precision.

Preliminary results will be incorporated into global analyses.

Abstract

The production of jets from polarized proton+proton collisions at STAR is dominated by quark-gluon and gluon-gluon scattering. The dijet double spin asymmetry (A\tsub{LL}) is sensitive to the polarized gluon distribution ($\Delta g(x)$). Dijets are also advantageous because the parton momentum fraction, x, of initial partons may be reconstructed to first order from the final state measurements. Both jet and dijet A\tsub{LL} measurements at $\sqrt{s}$ = 200 GeV have helped to constrain $\Delta g(x)$ in the range $0.05 < x < 0.3$. In 2012, data were collected at $\sqrt{s}$ = 510 GeV in order to probe lower values of x, these data are consistent with the $\sqrt{s}$ = 200 GeV results in the overlapping $x_T$ region. Jet and dijet preliminary A\tsub{LL} results have been released and will soon be incorporated into global analyses. In 2013, high luminosity data, with an estimated 250 pb$^{-1}$ of integrated luminosity were collected at $\sqrt{s}$ = 510 GeV. These data have a figure of merit of $\sim$3 times that of the 2012 data. An update on the dijet A\tsub{LL} measurement will be presented using polarized p+p data collected at STAR during 2013.